Featured Research

from universities, journals, and other organizations

How Montezuma Gets His Revenge

Date:

June 16, 2008

Source:

Johns Hopkins Medical Institutions

Summary:

Every year, about 500 million people worldwide are infected with the parasite that causes dysentery, a global medical burden that among infectious diseases is second only to malaria. In a new study appearing in Genes and Development, researchers may have found a way to ease this burden by discovering a new enzyme that may help the dysentery-causing amoeba evade the immune system.

Share This

Every year, about 500 million people worldwide are infected with the parasite that causes dysentery, a global medical burden that among infectious diseases is second only to malaria. In a new study appearing in the June 15 issue of Genes and Development, Johns Hopkins researchers may have found a way to ease this burden by discovering a new enzyme that may help the dysentery-causing amoeba evade the immune system.

Related Articles

"This is the first enzyme to be identified that looks like it could mediate immune system evasion," says Sin Urban, Ph.D., an assistant professor of molecular biology and genetics at Hopkins.

The EhROM1 enzyme, it turns out, is part of an ancient group of enzymes--they are found in every branch of life from bacteria to man--known as rhomboid enzymes. In most animals, rhomboid enzymes seem to play a role in cell-to-cell communication, but a couple of years ago Urban found that malaria parasites use rhomboid enzymes for a more sinister purpose: to enter host cells uninvited.

That led his team to scour the DNA of other parasites to see if any of them also had genes that encode rhomboid enzymes. They found that the dysentery-causing amoeba Entamoeba histolytica contains one rhomboid enzyme and named it EhROM1.

"Plasmodia, the parasites that cause malaria, grab onto a host cell and push their way in," explains Urban. "Once inside they use rhomboid enzymes to cut themselves loose." But amoebas don't enter cells to cause dysentery, so Urban's team set out to figure out how these parasites use EhROM1.

They first identified protein targets cut by EhROM1 by looking for amoeba proteins that had structural signatures similar to those cut by malaria rhomboids. They found these signatures in a family of proteins--lectins--that are found on cell surfaces. The researchers put both proteins into cells and verified that EhROM1 does cut one particular lectin, and the more EhROM1 they added, the more lectin pieces resulted.

Every cell has on its surface proteins recognizable by sentries of the immune system that constantly survey the body for intruders, and amoebas are no different. To evade the immune system, amoebas shift all their surface proteins to the rear end of the cell then, like a dump truck, shed these proteins into the fluid around them.

Lectin, it turns out, is one of the proteins that during immune evasion moves to the rear and is shed by the amoeba. So collaborating researchers at Stanford University then looked to see if EhROM1 follows lectin and sure enough found that EhROM1 clusters at the cap--the cluster of surface proteins waiting to be shed.

"We're excited to see if EhROM1 plays a specific role in the cap shedding during immune evasion," says Urban.

What's more, the EhROM1 enzyme is remarkably similar to those found in malaria parasites, suggesting that any potential drugs targeting EhROM1 might be able to treat two of the world's most prevalent diseases.

The research was funded by the National Institutes of Health and the Burroughs-Wellcome Fund.

Authors on the paper are Leigh Baxt and Upinder Singh of Stanford University, and Rosanna Baker and Urban of Hopkins.

More From ScienceDaily

More Plants & Animals News

Featured Research

Mar. 3, 2015 — While studying a ground-nesting bird population near El Reno, Okla., a research team found that stress during a severe weather outbreak of May 31, 2013, had manifested itself into malformations in ... full story

Mar. 3, 2015 — The 3-D printing scene, a growing favorite of do-it-yourselfers, has spread to the study of plasma physics. With a series of experiments, researchers have found that 3-D printers can be an important ... full story

Mar. 3, 2015 — Most people consume more salt than they need and therefore have a higher risk of heart disease and stroke, which are the two leading causes of death worldwide. But a new study reveals that dietary ... full story

Mar. 3, 2015 — By examining the forces that the segments of mosquito legs generate against a water surface, researchers have unraveled the mechanical logic that allows the mosquitoes to walk on water, which may ... full story

Mar. 3, 2015 — Pediatric otolaryngologists and surgeons are concerned with parents getting the wrong message regarding the safety/desirability of letting babies and young children eat peanuts to prevent them from ... full story

Mar. 3, 2015 — Researchers have developed a new way of rapidly screening yeasts that could help produce more sustainable biofuels. The new technique could also be a boon in the search for new ways of deriving ... full story

Mar. 3, 2015 — Similar to humans and animals, plants possess an innate immune system that protects them from invading pathogens. Molecular structures that only occur in pathogens enable their recognition and ... full story

Mar. 3, 2015 — For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth's oceans: Why does calcium carbonate, the tough material of seashells and corals, ... full story

Mar. 3, 2015 — To simulate chimp behavior, scientists created a computer model based on equations normally used to describe the movement of atoms and molecules in a confined space. An interdisciplinary research ... full story

Featured Videos

Rare Goblin Shark Found in Australia

AFP (Mar. 3, 2015) — A goblin shark, a rare sea creature described as an &apos;alien of the deep&apos; is found off Australia and delivered to the Australian Museum in Sydney. Duration: 01:25
Video provided by AFP

Zookeepers Copy Animal Poses In Hilarious Viral Photos

Buzz60 (Mar. 2, 2015) — Zookeepers at the Symbio Wildlife Park in Helensburgh, Australia decided to take some of their favorite animal photos and recreate them by posing just like the animals. Jen Markham (@jenmarkham) has the story.
Video provided by Buzz60

Related Stories

Oct. 25, 2012 — In the 1700s-1800s, dysentery was a disease causing many deaths. In fact, in some areas in Sweden 90 percent of all deaths were due to dysentery during the worst outbreaks. New research presents ... full story

July 16, 2012 — Researchers have genetically modified a bacterium commonly found in the mosquito’s midgut and found that the parasite that causes malaria in people does not survive in mosquitoes carrying the ... full story

Jan. 18, 2012 — Scientists have discovered a molecule that is key to malaria's 'invisibility cloak.' The research will help to better understand how the parasite causes disease and escapes from the ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.